If leading from the periphery can result in far reaching, rapid and decentralized waves of risk taking in a society, then it is important to understand the logic of such persistent vanguardism at the margins of the network. The dynamics of its spread from the hardened and highly connected, albeit marginal, cells of contention are to be different from centralized and well coordinated collective action. Marginal cells of contention as sources of collective action induce singular dynamics. In this chapter, I introduce these dynamics in the context of a number of basic network models.

There is extant evidence on the importance of marginals in inciting risky behavior and innovation adoption. For some time the idea of marginal man, as the motivating force behind transgressions from the social norm gained ground, and gave force to qualitative evidence on the singular role played by those not burdened by assuming regularities of a well established social role.

A theory of leading from the periphery needs to address two main issues: first, what are the conditions under which marginal instigators can sustain and preserve social innovation? And second, how such beginnings can travel far in the social network, recruiting themajority of a population into adopting a new social norm, a new technological innovation, a novel religion or ideology.